Rectifier



Sept. 27, 1949. W 2,482,777

RECTIFIER Filed NOV. 21. 1946 IN V EN TOR. HZ BE? 7' f. f/OWf A TTOPNE'Y Patented Se t. 27, 1949 RECTIFIER Albert E Howe, Richmond Hill, N. Y., assignor to Federal Telephone and Radio Corporation, New York, N. Y., a corporation of Delaware Application November 21, 1946, Serial No. 711,423

' ducing or destroying the electrical connection.

An object of this invention is to minimize such corrosion in dry rectifiers utilizing contact connections.

Another object is to provide an improved rectifier assembly having electrode contact connections.

Important features of the invention are the provisions of point contact for electrical connections, adequate spacing of elements for ventilation cooling and point applications, and light resilient pressure for the point contacts applied to the counterelectrode.

The invention is defined in the appended claims and one embodiment thereof is described in the following specification and shown in the accompanying drawing, in which:

Fig. 1 shows an elevational view with the lefthand half in section of a rectifier stack embodying this invention;

Fig. 2 is a sectional viewtaken substantially along line 22 of Fig. 1 with a part broken away to show details of a resilient point contact memher; and

Fig. 3 shows a detailed and enlarged crosssectional view of the boss or point contact region of the resilient contact member and one of the rectifier elements.

The particular rectifier illustrated comprises an assembly or stack of rectifier discs and other circular parts held on the draw bolt i, the bolt being insulated from all parts of the rectifier by a continuous insulating sleeve 2, extending between the nuts at opposite ends of the bolt. Two separate rectifier assemblies 3 and 4 with three flattened terminal leads 5, 6 and I, are shown although more or fewer assemblies may be mounted on the one bolt. Each assembly comprises a metal plate 8 on the one side of which is applied a semi-conductor layer 9 such as selenium covered substantially with a layer of counterelectrode alloy I0.

If desired metal plates with other semi-conductor material such as copper-oxide may be used in place of the selenium type of rectifier.

9 Claims. (Cl. 175-366) in series arrangement, it will be clear that they may be arranged back-to-back as in a full-wave rectifier. 'Also, while two assemblies have been shown, it will be understood that only one may be used, or if desired three or more may be employed.

Electrical contact is made to the outer layer Ill by a slightly concaved disc ll of springy metal such as Phosphor bronze or steel. A plurality of evenly spaced point-like bosses l2 are die pressed in the disc along the edge of the disc, and radial slots l3 are cut in the discbetween the bosses. Pressure against the convex side of the disc firmly holds each boss against the layer Ill.

Contact is made-to the back side of each plate and to each disc with an assembly of three or more evenly spaced metal pins I4 disposed around and parallel to the bolt. The ins are rounded on their ends and are held in place with an annular member l5 suitably perforated to receive the pins. The terminal leadsi, 6 and 1, pin members I5, discs II and coated plates 8 are each centrally apertured to slide easily over the insulating sleeve 2, and to assemble, the parts are placed on the sleeve and the bolt nuts tightened. Spacing washers or shims iii are sandwiched between the disc and the plate to limit the pressure on and distortion of the discs, while permitting considerable pressure at the bearing points of the pins.

Now, the rectifier thus assembled may be painted with a protective coating I! Fig. 3, of shellac, varnish, lacquer or pigment bearing oils, and according to an important feature of the invention, the protective coating may be easily applied to all metal surfaces, and whether the assembly is sprayed, dipped or brushed, a uniform heavy coating will entirely cover the metal and the semi-conductor surfaces. Yet there are no recesses or corners to trap globules of the liquid coating and prevent drainage and proper drying and curing of the coating material. Windows of any desired shape and size may be cut in the disc in addition to the radialslots to ventilate the space inside the disc concavity, andto admit and drain the coating material during manufacture.

In operation, when the parts expand and contract with heating and cooling, the pressure between the bosses l2 and the semi-conductor surface remains substantially constant and the relative movement between these parts is insufllcient to break the paint seal around the bosses.

Further, while the assemblies 3 and 4 are shown Even after the coating material becomes aged the 3 contact area under the bosses l2 remains eifectively sealed. The ends of the pins ll and the fiat metal surfaces under the pins are likewise enclosed and sealed in the protective coating material.

The improved rectifier of this invention is thus characterized by freedom from corrosion in the vital point contact parts. It should be noted that all contact areas are of point" dimensions. This eliminates large contact areas that may pocket moisture during manufacture, thereby avoiding troublesome corrosion. It also produces concentrated contact pressure thereby insuring good electrical connection.

I claim:

l. A rectifier comprising a metal plate, a semiconductor layer on said plate, a contactor having a plurality of rounded metal points bearing against said semi-conducting layer, terminal leads, means to provide electrical point contact with respect to said leads, said contactor, and said plate, respectively, and a protective film covering said assemblage enclosing and sealing each point contact region.

2. A rectifier comprising a metal plate, a semiconductor layer on said plate, a metal disc, rounded bosses formed on one side of said disc near the edge of the disc and bearing against said semiconductor layer, and terminal leads connected through point contact respectively to said plate and to said disc.

3. The rectifier defined in claim 2, including said disc, said disc having openings therethrough into the space between said plate and disc.

4. The rectifier defined in claim 2, including a metal pin perpendicular to said plate and bearing at opposite ends against said plate and one of said terminal leads.

5. The rectifier defined in claim 2, including a metal pin perpendicular to said plate and bearing at opposite ends against said disc and one of said terminal leads.

6. The rectifier defined in claim 2, including a plurality of metal pins perpendicular to the platedisc assembly, and between said assembly and one of said terminal leads, an annular member for holding said pins in spaced parallel relation, an insulated bolt extending centrally through said plate, disc, member, and terminal lead for drawing the pins into pressure contact with said lead and assembly.

7. The rectifier defined in claim 2, including a continuous protective coating on said bosses and on said semi-conductor layer around said bosses and the point contacts electrically connecting the terminal leads to said plate and to said disc.

8. A rectifier comprising a metal plate, a semiconductor layer on said plate, a concaved metal disc with bosses spaced along the edge of said disc on the concaved side thereof, said disc and plate being coaxial with said bosses bearing against said semi-conductor layer, an insulated bolt extending centrally through said disc and plate, a plurality of pins symmetrically arrayed around and parallel to said bolt and bearing against said plate, a plurality of pins symmetrically arranged around and parallel to said bolt and bearing against said disc, flattened terminal leads bearing against the outer ends of said pins, a threaded nut on said bolt for tightening the bearing points between said pins, disc, plate and terminal leads, and a protective coating on and around said hearing points.

9. A rectifier comprising a metal plate, a semiconductor layer on one side of said plate, a concaved metal disc with bosses formed on the concaved side of said disc near the periphery of the disc, said bosses being held under pressure against said layer, electrical terminal point connections to said plate and disc, respectively, and a protective coating on all exposed surfaces of said plate, layer, and disc.

ALBERT E. HOWE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,134,131 Kpphan .2 Oct. 25, 1938 2,153,434 Schimkus Apr. 4, 1937 2,221,616 Smith Nov. 12, 1940 2,302,087 Addink et al Nov. 1'7, 1942 2,316,553 Brunke Apr. 13, 1943 

